Integrated Brushless Direct Current Motor and Lift Pump

ABSTRACT

A lift pump having a longitudinal axis and comprising first and second housing components defining an operational volume, a brushless direct current motor assembly, and a pump assembly disposed in said volume. The brushless direct current motor assembly has a motor axis eccentric with the longitudinal axis, a rotor, and a stator disposed diametrically inwardly of the rotor. The rotor further comprises a plurality of magnetic poles of alternating opposite polarity. The pump assembly has a pump annulus and a pump element. The pump annulus is disposed intermediate said first and second housing components and coaxial with the longitudinal axis. The pump element is coaxial with said motor axis, and comprises a generally cylindrical hub defining a motor assembly cavity sized to diametrically receive said motor assembly.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates to fluid pumps, and more particularly to an integrated brushless direct current (BLDC) motor and fluid pump.

Prior art fluid pumps are utilized in a multitude of applications, such as cooling systems for electronics, home heating and ventilation, and automotive systems. Fluid pumps may move blood, water, gasoline, oil, transmission fluid, air, hydraulic fluid, jet fuel, and other fluids.

Fluid pumps may be powered by an electric motor to create the force necessary to move fluid. Typical BLDC motor powered pumps have discrete motor and pumping sections. Such prior art pumps include motor and pumping sections mounted in series, or end to end. This configuration may make traditional pumps spatially inefficient, and provide limited output relative to the size of the component.

In automotive systems, traditional BLDC motor powered pumps are typically mounted either vertically or horizontally in the engine compartment. Vertically mounted BLDC motor pumps may utilize a separate pump housing and a filter may be selectively mounted axially to the pump. The vertical configuration utilizing a filter requires additional space to ensure the filter can be removed and replaced as necessary.

Horizontally mounted BLDC motor pumps may be mounted above the header and perpendicular to the chassis. The efficiency and durability of horizontally mounted pumps can be adversely affected by engine vibration. The horizontal configuration of such pumps traditionally requires that a mechanic disassemble the pump or the header when servicing either component.

Additionally, the relative position of the rotor and stator in prior art BLDC motor pumps may restrict the types of materials that may be used. Because the moving pump element is typically coupled to the rotor, and the stator is arranged radially outside of the pump element, components such as the rollers in a roller vane pump element must be constructed of a non-ferrous material.

Accordingly, there is a need for a powerful, yet compact BLDC motor powered fluid pump.

SUMMARY

According to aspects of the disclosure, a lift pump comprises first and second housing components, a pump assembly, a BLDC motor assembly, and a pump annulus. The first and second cover plates shown in the present disclosure are specific to a prototype construction employed for a proof of concept device. These cover plates are likely to be combined with other packaging or housing features of a commercial assembly and are not necessarily indicative of a production design. The disclosed cover plates may alternatively be described as “first and second housing portions” configured to mate and define the operational volume for the BLDC motor assembly and pump. The first and second housing portions may define fluid passages and paths for electrical conductors supplying power and control to the BLDC motor.

For example, the integrated motor and pump may be manufactured as part of a filter header. The outer body of the pump and non moving components can be integral to the filter header. The moving components may then be assembled directly into the header. Alternatively, the pump may be packaged independently or combined with other components, such as a heater and a filter assembly.

The integrated motor and pump is disclosed in the context of a fuel supply system for a motor vehicle, but the pump may be used to deliver any fluid, including but not limited to blood (or other body fluids), water, fuel, oil, air, gasoline, transmission fluid, jet fuel, refrigerant, hydraulic fluid or the like. The outrunner configuration can be employed to drive alternative pump configurations, including rotary vane, gerotor, flexible vane, gear, turbine, roots—positive displacement pumps and also centrifugal pumps.

In one embodiment, the first and second cover-plates define an inlet and an outlet, respectively. The pump annulus is disposed intermediate the first and second plates, and defines a fluid-tight pump cavity. The motor assembly and pump assembly are packaged in parallel, and received in the pump cavity. The first and second cover-plates and pump annulus are connected to define the pump cavity. The first and second cover-plates, and pump annulus are coaxial with a longitudinal pump axis.

The motor assembly has a motor axis eccentric with the pump axis, and comprises an outrunner motor. The motor is configured such that the stator is disposed diametrically inwardly of the rotor. The stator comprises a number of discrete groups of coils or windings disposed radially outwardly of the motor axis, and which may be selectively energized to produce a rotating magnetic field. The rotor comprises an annulus having a plurality of magnets alternating in polarity, and disposed diametrically outwardly of the stator.

The pump assembly comprises a pump element having a cylindrical hub which defines a motor assembly cavity. The hub acts as a flux ring, shielding the remainder of the integrated pump from the magnetic field created by the components of the motor assembly. In one embodiment the pump element comprises a roller vane. In an alternate embodiment the pump element comprises a gerotor assembly but also could be an alternate positive displacement pump (gear pump) or centrifugal pump (i.e. turbine).

Integrating the motor assembly within motor assembly cavity of the pump element hub has a number of advantages. The more compact profile resulting from mounting the elements of the integrated lift pump in parallel with the motor assembly allows for a wider range of uses. For instance, the pump may be built integral with a filter header where space is otherwise limited. Reducing the number of components and removing the need for a discrete housing unit to package the separate pump and motor simplifies assembly, thereby reducing assembly time and component manufacturing cost.

When used as a fluid pump, integrating the pump assembly and motor assembly allows the fluid to act as a coolant. As a result of a cooler running “wetted” configuration, the pump can pump a greater volume at higher pressure than in a non-wetted configuration.

By creating a flux ring within the pump element, the integrated lift pump may be used in a number of applications where magnetic fields generated by the motor are otherwise undesirable. The components of the pump assembly, in particular the roller vanes, can be manufactured from ferrous or other materials susceptible to magnetic forces.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the preferred embodiment will be described in reference to the Drawing, where like numerals reflect like elements:

FIG. 1 is an exploded view of one embodiment of an integrated lift pump employing a roller vane pump configuration;

FIG. 2 is a perspective exterior view of the integrated lift pump of FIG. 1 in an assembled configuration;

FIG. 3 is an exploded view of a second embodiment of an integrated lift pump employing a gerotor pump configuration;

FIG. 4 is an enlarged perspective view of the first plate and stator from the embodiment of the integrated lift pump depicted in FIG. 1; all other elements of the integrated lift pump are omitted for clarity;

FIG. 5 is an enlarged perspective view of the roller vane pump element from the embodiment of the integrated lift pump depicted in FIG. 1; all other elements of the integrated lift pump are omitted for clarity; and

FIG. 6 is an exploded perspective view of the embodiment of the integrated lift pump depicted in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of an integrated BLDC motor and lift pump will now be described with reference to the drawings wherein like numerals represent like parts throughout FIGS. 1-6. FIG. 1 illustrates an embodiment of an integrated BLDC motor and lift pump 10, according to aspects of the disclosure. It will be noted that the illustrated construction is based on the simplified components of a proof of concept embodiment of the integrated BLDC motor and lift pump. A production embodiment of the disclosed BLDC motor and lift pump will likely incorporate the disclosed first and second cover plates into other components of a filter assembly header or base module. Thus, the disclosed BLDC motor and lift pump are not limited to the disclosed component configurations, which may be combined with other components or modified to facilitate manufacture and assembly.

The integrated pump 10 has a longitudinal pump axis A-A and first and second cover-plates 12 and 14, respectively. In one embodiment the first cover-plate 12 defines an inlet 16, while the second cover-plate 14 defines an outlet 18. In an alternate embodiment depicted in FIG. 3, the first cover plate 12 defines both the inlet 16 and the outlet 18. Though two flow configurations are illustrated in the figures and described herein, other flow configurations may be utilized without departing from the scope of the disclosure.

With reference to FIGS. 1 and 3, the BLDC motor assembly 20 is disposed intermediate the first and second cover-plates 12 and 14, and coaxial with a motor axis B-B, eccentric with the longitudinal pump axis A-A. The motor assembly 20 is configured as an outrunner motor. A stator 22 is disposed diametrically inwardly of and concentric with a rotor 24.

In one embodiment illustrated in FIG. 4, the stator 22 comprises an armature assembly 23 having a plurality of members 27 that extend radially away from a central hub 25. A number of windings or coils 26 which are operatively connected to a control circuit 21 (FIG. 2) are disposed on the ends of the members 27 radially opposite the hub 25. The control circuit 21 selectively provides current to the windings 26 to generate a rotating magnetic field. In one embodiment, the second plate 14 defines a shallow stator cavity 29, and the stator is disposed within the cavity 29.

The control circuit 21 may be configured to selectively operate the motor 20 to run the rotor in a clockwise or counter-clockwise direction. Programming the control circuit 21 to selectively reverse the flow of fluid through the lift pump 10 allows the user to drain the system before servicing any of the constituent parts, and prime the pump 10 afterwards.

The control circuit 21 is additionally programmable to adjust the speed and torque throughout the life of the pump 10. As the elements of the pump assembly 30 wear in the course of normal operation, the efficiency of the pump decreases. To compensate for the drop in pump efficiency, the control circuit 21 increases the speed and torque to ensure that lift pump 10 output remains constant.

The rotor 24 comprises a plurality of alternating opposite magnetic poles 28. A number of suitable materials and configurations are contemplated in connection with the current disclosure. In one embodiment shown in FIG. 1, the alternating magnetic poles 28 comprise a plurality of magnets, arranged in an annulus concentric with the motor axis B-B, and disposed diametrically outwardly of the stator 22. In another embodiment, the alternating magnetic poles 28 comprise a single multipole magnet having alternating opposite poles. As the control circuit selectively energizes the individual windings 26 of the stator 22, the stator 22 drives the alternating magnetic poles 28 of the rotor 24.

The motor assembly 20 is packaged in parallel with a pump assembly 30 in a “wetted” configuration. Packaging the motor assembly 20 in parallel with the pump assembly 30 allows the fluid pumped through the system to simultaneously act as a coolant, allowing the BLDC motor to run cooler and pump fluid at higher pressures than attainable with a non-wetted configuration.

As best seen in FIG. 5, the pump element 32 has a generally cylindrical hub 34 defining a motor assembly cavity 35. The motor assembly cavity 35 has a diametrical width w sized to diametrically receive the motor assembly 20, and a depth d. The alternating magnetic poles 28 of the rotor 24 are received in an annulus press-fit within the motor assembly cavity 35. In this embodiment, the hub 34 acts as a flux ring when the motor assembly 20 is actuated, containing the magnetic field produced by the motor assembly 20. The hub 34 effectively shields the magnetic field produced by the motor assembly 20 from interfering with the other components of the lift pump 10. As a result, the constituent elements of the pump assembly 30 may be manufactured from components comprised of ferrous or other materials susceptible to magnetic forces without compromising the efficiency of the integrated pump 10. In another embodiment, the alternating magnetic poles 28 are integral with the hub 34.

In one embodiment depicted in FIGS. 1, 4, and 5, the pump element 32 comprises a roller vane. The roller vane pump element 32 comprises a generally circular main body 38. The generally cylindrical hub 34 extends axially away from a main surface 36 of the main body 38. A plurality of roller hollows 40 are defined at equal distances along a radial periphery 42 of the main body 38. A generally cylindrical roller 44 is received in each of the plurality of roller hollows 40.

In one embodiment depicted in FIGS. 1, 4 and 5, the roller vane has an axle 46, which is received in an axle cavity 48 defined in the motor assembly cavity 35. In this embodiment, the roller vane axle 46 is received by a bushing 50 which is disposed diametrically interior the hub 25 of the stator armature 23. In one embodiment, the roller vane axle 46 is coaxial with the motor axis B-B and eccentric with the longitudinal pump axis A-A.

In an alternate embodiment depicted in FIGS. 3 and 6, the pump element 32 comprises a gerotor assembly. With reference specifically to FIG. 6, the gerotor pump element 32 comprises inner and outer gerotors 52 and 54, respectively. The inner gerotor 52 and outer gerotor 54 are generally annular. A variable number N of teeth 53 project radially outwardly from an outer surface 56 of the inner gerotor 52. The number N of teeth 53 varies depending upon the size of the pump and the power output required in the specific application. Regardless of the size or power output required, the outer gerotor 54 always has the number N+1 teeth 55 that project radially inwardly from an inner surface 58 of the outer gerotor.

In one embodiment, an inner surface 60 of the inner gerotor 52 defines the motor assembly cavity 35. In this embodiment, the motor assembly rotor 24 is received within the motor assembly cavity 35 of the inner gerotor 52. A gerotor axle 62 extends through the rotor 24 and is received by first and second bushings 64 and 66. The first and second bushings 64 and 66 are received in the first and second plates 12 and 14, respectively.

In one embodiment, the rotor 24 and motor assembly cavity 35 of the inner gerotor 52 are sized such that a press-fit connection is established between the rotor 24 and the motor assembly cavity 35. In an alternate embodiment the motor assembly rotor 24 and the inner gerotor 52 can be manufactured as a single unitary element.

Referring to FIGS. 1 and 3, when completely assembled, the motor assembly 20 and pump assembly 30 are received diametrically within a pump cavity 68 defined by a pump annulus 70. The pump annulus 70 has a height h, which is sized to receive the motor assembly 20 and pump assembly 30.

The height h of the pump annulus 70 is variable, as the size of the alternating opposite magnetic poles 28 and the selectively energizeable coils 26 may be altered to generate more torque. Adjusting the axial height of the coils 26 and magnetic poles allows for the motor assembly 20 to create more torque while utilizing the same pump assembly 30.

In the embodiment shown in FIGS. 1-6, the axial height of the alternating magnetic poles 28 and coils 26 is generally the same as the depth d of the motor assembly cavity 35. In an alternate embodiment (not shown), the coils 26 and alternating magnetic poles 28 have an axial height larger than the depth d of the motor assembly cavity. Accordingly, the rotor and stator project axially above the hub 34.

The assembled integrated lift pump 10 is compact and markedly less bulky than prior art BLDC motor-powered lift pumps. The pump components are configured to provide a substantially sealed operational volume for the motor and pump. A sealed configuration may be achieved by manufacturing the components with close tolerances, or the components may be provided with appropriate seals, gaskets or the like.

In automotive settings, the integrated lift pump may be utilized in a number of novel applications because of the pump's compact profile. For example, the pump can be used for intermittent duty cycle, which is optimal in a priming only fuel delivery system.

The compact profile of the assembled lift pump 10 also makes it possible to integrate a filter header with the lift pump 10 to simultaneously filter and deliver fuel to a fuel injection pump (not shown). Given the compact size and reduced part count of the integrated lift pump 10, the motor assembly 20 and pump assembly 30 may be directly installed into a filter header, saving space by eliminating the need for a separate, bulky fuel pump.

Additionally, the pump can be utilized as a reversible fuel pump, delivering fuel to and from the tank. By making the fuel pump reversible, the life of the filter may be extended by back-flushing the filter element.

While preferred embodiments have been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit of the invention and scope of the claimed coverage. 

What is claimed is:
 1. A lift pump having a longitudinal axis comprising: first and second housing components defining an inlet, an outlet, and an operational volume; a brushless direct current motor assembly having a motor axis eccentric with the longitudinal axis, a rotor comprising a plurality of magnetic poles arranged in alternating opposite polarity, and a stator comprising a number of selectively energizeable coils disposed diametrically inwardly of said rotor annulus; and a pump assembly having an inlet and outlet including a pump annulus coaxial with the longitudinal axis, a pump element coaxial with said motor axis and having a generally cylindrical hub defining a motor assembly cavity having a diametral width w and an axial depth d, wherein said motor assembly cavity is sized to diametrically receive said motor assembly so that said pump element rotates with said rotor.
 2. The lift pump of claim 1, wherein said plurality of magnetic poles comprise a plurality of individual magnets of alternating opposite polarity affixed to an annulus, and said annulus is secured diametrically within said motor assembly cavity.
 3. The lift pump of claim 1, wherein said plurality of magnetic poles comprise a single multipole magnet having alternating opposite poles.
 4. The lift pump of claim 1, wherein said plurality of magnetic poles are integral with said hub.
 5. The lift pump of claim 1, wherein said pump element is a gerotor pump having an inner and outer rotor, said inner rotor having said pump annulus.
 6. The lift pump of claim 1, wherein said pump element is a roller vane pump.
 7. The lift pump of claim 6, wherein rollers of said pump comprise a ferrous material.
 8. The lift pump of claim 6, wherein rollers of said pump comprise a non-ferrous material.
 9. The lift pump of claim 1, wherein an axial height of said stator coils and said magnetic poles is larger than said depth d of said motor assembly cavity. 